Marseille , France -LRB- CNN -RRB- Initial tests on the flight data recorder recovered from downed Germanwings Flight 9525 show that co-pilot Andreas Lubitz purposely used the controls to speed up the plane 's descent , according to the French air accident investigation agency , the BEA .

The flight data recorder , or `` black box , '' was found Thursday by recovery teams that have spent days since the March 24 crash scouring the mountainside in the French Alps where the plane went down .

A statement from the BEA on Friday said its teams had immediately begun to investigate its contents .

`` The initial readout shows that the pilot present in the cockpit used the autopilot to put the -LRB- airplane -RRB- into a descent towards an altitude of 100 -LRB- feet -RRB- then , on several occasions during the descent , the pilot modified the autopilot setting to increase the speed of the -LRB- airplane -RRB- in descent , '' it said .

`` Work is continuing to establish the precise history of the flight . ''

Evidence from the plane 's cockpit voice recorder , recovered swiftly after the crash , had already led investigators to believe that Lubitz acted deliberately to bring down the plane , killing all 150 people on board .

And prosecutors in Germany said Thursday that an analysis of a tablet device retrieved from the 27-year-old 's apartment in Dusseldorf revealed that he had researched suicide methods and cockpit door security on the Internet .

The correspondence and search history on the device demonstrated that the co-pilot used it from March 16 to March 23 , Dusseldorf prosecutor Christoph Kumpa said .

The search history was not deleted and also revealed searches concerning medical treatment , the prosecutor said .

Investigators have focused on Lubitz 's health as they try to establish his motivation .

But the missing `` black box '' was expected to yield important evidence about the plane 's final minutes .

A female police officer digging by hand for clothes in a ravine that been searched previously found the flight data recorder Thursday afternoon about 8 inches -LRB- 20 centimeters -RRB- below the surface , Marseille prosecutor Brice Robin told reporters .

Usually white with florescent orange , this discovered recorder lived up to its name as a black box because fire had darkened it with ashes .

In addition , out of more than 2,000 DNA samples collected from the crash site , lab workers have isolated 150 DNA profiles , Robin told reporters .

`` That does not mean we 've identified '' the crash 's 150 victims , Robin said -- noting the recovered DNA still must be compared with DNA submitted by the families of those who died in the crash .

Authorities have also found 470 personal effects at the site , according to Robin . That number includes 40 cell phones , though all those were badly damaged . Robin cast doubt that any useful information could be retrieved from those phones , given their condition .

That view is consistent with French officials ' claims Wednesday insisting that two publications , German daily Bild and French Paris Match , were wrong to report that cell phone video showed the harrowing final seconds from on board the flight .

Noting he 's made a criminal request to German authorities but is for now conducting his own investigation , the French prosecutor said he is tasked with an involuntary homicide investigation .

But Robin noted that Lubitz made voluntary actions -- such as guiding the plane toward the mountain and reducing its speed to prevent alarms from going off -- and was `` alive and conscious '' to the very end .

A European official government official with detailed knowledge of the investigation said that Lubitz 's actions amount to `` premeditated murder . ''

While cautioning that there are still many holes in understanding Lubitz 's motivation , the disclosures about his Internet searches show that he planned to do what he was going to do , according to this official .

Calls for crash avoidance technology

It is becoming increasingly clear to investigators that Lubitz was `` very afraid '' he would lose his license to fly because of his medical issues , a law enforcement source with detailed knowledge of the investigation told CNN on Thursday .

It 's already emerged that Lubitz had battled depression years before he took the controls of Flight 9525 and that he had concealed from his employer recent medical leave notes saying he was unfit for work .

But the law enforcement source said that after a severe depressive episode in 2009 , Lubitz relapsed with severe depression and stress in late 2014 .

In the weeks leading up to the crash , Lubitz was shopping doctors , seeing at least five , perhaps as many as six , the source said , as he kept going from one doctor to the next seeking help , including from a sleep specialist . He was prescribed powerful medication , though it 's not clear he was taking it .

Opinion : What if my patient is a pilot ?

CNN 's Margot Haddad reported from Marseille , and Laura Smith-Spark wrote from London . CNN 's Pamela Brown and Greg Botelho contributed to this report .

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French investigators : Flight data recorder reveals Andreas Lubitz acted deliberately to crash plane

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He used autopilot to set altitude at 100 feet and then used the controls to speed up the descent